Full range or subwoofer with bookshelfs for best bass at low to moderate volume?


I have an older subwoofer with bookshelf speakers and the subwoofer is dying. I listen mostly at low to moderate volume and am in the middle of changing over my system as my Pioneer Elite VSX 49 TXI receiver was degrading, also due to age. My question is whether a subwoofer with bookshelf speakers or full range speakers produce more bass at low to moderate volume? 

Current system:
Moon Audio 250i integrated amp
Angstrom signature 3 speakers ( 6.5", Seas drivers, 86 DB, 6 Ohm)
Paradigm subwoofer (needs to be replaced)
Denon 2910 used as transport
Looking for an analog sounding dac at this time

mtloriginal
near full range speakers (40 hz or so) with a quality , higher powered amplifier .
i used to have psb tower speakers that played solid down to 40hz and a good NAD amp rated at 150 watts / channel. a powerful amp controls the speaker motion extremely well and has the power to create dynamic bursts even at low volume. the bass was spontaneous, tight and incredible and you could feel the impact from the excursions at really low volume.
the sign of a quality amp is to see if its rating goes up with a lower ohm spec, example 150 watts at 8 ohms, 200 watts at 4 ohms.  a good sign that the amp has a solid design and large enough transformers to have reserve power.  
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Bookshelf + sub.
Because you will get the lowest hz, and because you can integrate it the way you want.
With a full range, boosting low frequecies is more challenging and you miss the 20s
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